Electric condenser



Oct. 25, 1932. A. KAZENMAIER ET AL ELECTRIC CONDENSER Filed July 28. 1927 10 ing which will cling tenaciously of the phenol-formaldehyde type,

, stances are Patented Oct. 25,1932

UNITED STATES PATENT OFFICE AUGUST KAZENMAIER AND WALTER DORN, OF STUTTGABT, GERMANY, ASSIGNOBS '20 ROBERT BOSCH .AKTIENGESELLSCEAFT, OF ST'UTTGART, GERMANY nnnc'rmc CONDENSER Application filed July 28,

5 conducting material and insulating or dielectric material.

A principal object of the invention is to provide a condenser of the above character with adurable, insulating, protective coatto the condenser and at the same time be impervious to moisture.-

Other objects of the invention will be apparent from the following description.

It is highly desirable to protect electric condensers of the above mentioned type with a coating of any of the many synthetic resins such, for as bakelite because such subhard and impervious to moisture. However, a coating of this material does not example,

adhere well to the metal surfaces of the conof its britso that densers and furthermore, because tleness, it is easily cracked or broken, such a coating is either start or becomes so after a short time.

It is also desirable to protect such condensers with a coating of shellac or similar gumlac or resinous substance because shellac adheres well to metal, is a good insulator and is comparatively elastic or non-brittle. However, a shel-lac coating of condensers is objectionable because it does not resist moisture.

According to the present invention the advantages of the above mentioned substances are combined and a durable, reliable, moisture-proof coating is secured by first coating the condenser with a solution of shellac and thereupon with a solution of a synthetic resin or phenolic condensation product such as bakelite. In this case, the protective coating of shellac, which adheres well to the metal parts, is in turn protected, especially from moisture, by the layer or coating of bakelite or the like. The shellac forms a binder between the layer of bakelite or the like and the metal parts. i

The accompanying drawing illustrates a condenser embodying our invention. The condenser-proper f defective from the cedure described above,

comprises two strips of.

1927, Serial No. 209,175, and in Germany August 28, 1926.

thin metal foil and two strips of insulating material rolled up into the form of a roll or cylinder. The four strips are arranged in the mannerwell known s9 that the strips of metal alternately are placed back from one edge of the insulating'strips and protrude over the other edge of said insulating strips. The protruding strips of metal are then pressed down against the ends of the rollto form metal layers or discs I) which are insulated from each other by the strips of insulating material. The condenser thus formed is inserted in a metallic-casing a, in which is inserted an insulating sleeve (1. One of the strips of metal foil is wound around and thereby connected with an inner metallic cylinder e, the lower disc I) being connected to the casing a. This casing is closed by an insulating disc 0 and the assembly thus formed is surrounded with a first coating layer 9 of shellac and a second protecting layer. h of artificial resin.

The shellac is applied to the condenser in any manner desired, the simplest way being by immersion, particularly if the condenser is to be coated all over. However, the shellac may be applied in other ways,- with a brush, for example, particularly if it is only a question of providing the condenser with a protective coating in places. The coating of artificial resin or bakelite may be applied in the same manner. is dried by the application of heat.

It is to be understood that the invention is not limited to the specific construction or probut that it includes all the modifications and adaptations which fall within the scope of the appended claims.

, \Vhat is claimed is:

1. A condenser provided with a. protective 90 coating on its metal surfaces comprising athin coating of a non-brittle resinous electrically insulating material and a thin outer coating of a-phenolic condensation product on the protective coating.

2. A condenser provided with a protective coating on its metal surfaces comprising a coating of shellac and an outer coating of a phenolic condensation product on the protec- 1 tive coating.

Thereupon the condenserbody Eroof material and a layer of insulating nonrittle resinous material between the metal 90 I 3. A condenser'provided with a protective coating on its-metal surfaces comprising a coating of a non-brittle resinous electrically 7 insulating material adhering to the condenser material adhering to said first coating.

4. Electrical apparatus having metal surfaces provided which clings tenaciously to the metal surfaces, said film coating comprisinga coating of a non=brittle I electrically insulating tenacious material placeddirectly on said metal surfaces and a film coating of a water-proof material placed directly on said-coating of non- .brittle material.

' 5. A condenser having a metalsurface provided with an outer coating layer of moisture surface and the outer layer, and adhering to" to the outer coating and thereby forming a binder between the metal surface and layer, them.

6; A condenser having ametal surface pros vided with an outer coating layer of a phenolic condensation product in between the metal-surface and adhering to both.

combination with an intermediate binding layer of shellac In testimony whereof we have hereunto aflixed our signatures. a

'AUGUST KAZENMAIER;

v WALTER DORN.

and an outer coating of a moisture-proof with a moisture-proof coating l and the outer layer, 

